The packaging of food and other products with a sheet of flexible plastic film through an automated process using a machine is typically achieved by butting and sealing the plastic film to form a pouch. There are numerous examples of such machines, which are referred to within the industry as form-fill-seal machines, and which may be further subdivided into categories as being either horizontal, vertical, or rotary form-fill-seal machines. An example of a horizontal form-fill-seal machine is shown by U.S. Pat. No. 5,826,403 to Haley; an example of a vertical form-fill-seal machine is shown by to U.S. Pat. No. 4,117,647 to Rossi; while an example of a rotary form-fill-seal machine is shown by U.S. Pat. No. 6,212,859 to Bielik.
For a substantial period of time, these form-fill-seal machines utilized heat elements, such as the “heated fin wheels” of the Haley device, to seal the package bottom and its side seam to create a pouch, and after filling that pouch with product, a final heat element would seal the top open end of the pouch to form the package. An early marriage of ultrasonic welding principles for sealing of plastic films with a packaging machine is shown by the 1981 U.S. Pat. No. 4,288,965 to James, for a “Form-Fill-Seal Packaging Method and Apparatus.” Ultrasonic welding has since become the preferred method of sealing, because, among other reasons, ultrasonic weld times are less than one second in duration, the process lacks the potential for damage to the packaging material or product from an excessive application of heat, for which traditional heating elements are susceptible, and because the ultrasonic welding process is much better suited to seal through contaminants and product, which the heat sealing process accomplishes poorly, if at all.
Our above-noted co-pending U.S. patent application Ser. No. 12/925,652 for “Sonotrode and Anvil Energy Director Grids for Narrow/Complex Ultrasonic Welds of Improved Durability,” furthers this divide. The technology disclosed therein makes even more advantageous the use of ultrasonic welding over heating elements, as it reduces the necessary material, by allowing for a narrower weld, while also simultaneously producing welds of improved durability, which is highly desirable particularly for the packaging of liquid, semi-liquid, and even for the packaging of solids or semi solid products. Of course, the process could still be used to produce wider welds, where they may be desired, for example for aesthetic purposes, rather than for being needed to produce a stronger, more durable seal.
However, while that patent-pending technology may easily be incorporated into newly designed form-fill-seal packaging machines, consumers who either recently or long ago purchased machines that seal through the direct application of heat have been at an impasse. The owner's of those machines do not wish or simply cannot afford the expense of a new array of packaging machines, nor can they afford to not produce packaging with the durability that their competitors will soon be utilizing through the use of machines incorporating this new apparatus. The problem has one added dimension of complexity.
The different types of packaging machines may dictate forming the pouch in different stages and at different locations within the machine. In addition, it is common to have at least one or even multiple heat seal stations just for the final top end sealing of multiple product-filled pouches. Therefore, it is highly desirable to incorporate our patent-pending ultrasonic welding technology onto existing machines, but attempts to accomplish such a retro-fit by package machine operators has been unsuccessful, because of the space-constrained volume allocated to the replacement unit. The current invention discloses an adaptable retrofit kit and method for successfully accomplishing retrofitting of the heat station for different kinds of form-fill-seal machines.